Petrology and tectonics of Early Cretaceous adakitic rocks in the Kitakmai Mountains, Japan

Abstract

Early Cretaceous igneous rocks in the Kitakami Mountains are diveided into volcanic rocks, dike rocks, and plutonic rocks. Plutonic rocks are composed mainly of adakitic granites in central part of zoned plutonic bodies surrounding by adakitic to non-adakitic granites in marginal part. The exposure of the adakitic plutons is divided into two zones: from the eastern part of the north Kitakami belt to the eastern margin of the south Kitakami belt (E zone), and the inner part of the South Kitakami belt (W zone). Zircon U-Pb age of the adakitic granites in W zone are younger than those in E zone, they are considered to be derived from higher pressure and vapor-present condition.